Method of preparing cast explosive charges



l'aiented. Sept. ll, 15

ism E. Kit-st, Woodbm'y, ore to E. I. du Pont de Nemours & Wu, Del, a. notion o! No Dre. Application Ant 7. 1m,

Serial No. msss 5 fisims.

This invention relates to cast explosive charges and more particularly to a. more advantageous method for the preparation of blends of trinitrotoluene and pentaerythritol tetranitrete.

In the preparation of these blends, it has been the practice of the art to employ carefully dried pentaerytln'itol tetranitrate. There have been attendant difllcult-ies in that lumps are formed on addition to molten TNT.

This application is a continuation in port of ing trinitrotoluene and pentaerythritol tetranitrate. A still further object is such a. method in which increased efliciency in handling the ingredients results, and in which safety in operation is promoted. Additional objects will be disclosed as the invention is described more in detail hereinafter.

We have found that the foregoing objects are accomplished when we utilize pentaerythrltol tetranitrate wet with water and bring it into mixture with trinitrotoluene. The latter in molten condition is contacted-with the pentaerythritol tetranitrete, end the water present in this latter material will rise to the surface. It can then be decanted, drawn or skimmed on, or removed in any desired manner.

Two procedures may be followed in oh the mixture of PETN with molten TNT. For example, we may bring the TNT into molten form and introduce the wet PETN thereinto. -.We may, on the other hand, blend the solid TNT with the wet PETN and then raise the temperature above the fusion point of the lower melting compound. If desired, both esploflve materials may be introduced into water and the temperature of said water. he raised above the fusion point of the TNT, for example, by the e or steam. whatever the procedure, when the wet PETN becomes blended with molten TNT, the water present rises to the surface and may be removed therefrom The pentaerythritol tetranitrate available for commercial use is ordinarily in wet form. The

regulations require that this explosive for shipping shall have a. water content or at least 40% and material in storage in larse amounts should have no less water content. Consequently, the

material available for use will ordinarily be in very wet form. The drying of wet pentaerythrito! tetranitrate is time-consuming and is accomplished with considerable hazard. The discoverythereiore that wet pentaerythritol tetranltra 1 can be satisfactorily introduced into the melt is a, very important advance.

In pg cast blends of TNT and PETN, the mixture or the two is prepared and the TNT maintained in molten condition at a. temperature between its melting point and 100 C. The PETN is desirably in relatively finely divided condition and thoroughly mixed with the TNT by agitation. A water layertorms almost immediately on top of the melt and this wamr can be drawn ofi readily, leaving normally less than 5% of/water in the molten blend. The melt can be formed and handled satisfactorily in steam Jacketed metal containers. Under such conditions, the greater part of the residual water in the melt will be removed byevaporationin a relatively short time. We find it desirable, however, to hasten the removal of the water by passage of air throush the melt. It is desirable to dry the material to a. moisture content not greater than 0.1%.

, Various compositions of such blends of trinitrotoluene with pentserythritol' tetranitmte can be prepared having desirable explosive properties. We find a -50 composition to give satisfactory results and, generally speaking. prefer to maintain the composition within the range or 35-75% Dentaerythritol tetranitrate and 25% trinitrotoluene. It will be understood that in such blends the .trinitrotoluene is the continuous phase. with pentaerythritol tetra-nitrate as examples or methods employed to prepare blends in accordance with the foregoing description.

Example 1 Two 5000-srsm batches (about 11 lbs. each) were prepared by adding to molten trinitrotoluene heated to 08 C. pentaerythritol tetraunheated pentaerythritol tetranltrate was added inZOO-SOOBmmIotsatsuchemtethetthe melt temperature remained htween -80 C.

1: Example 1! Two 4000-gram-batches (8.8 lbs. each) were prepared of 50-50 blends in a manner similar to that of Example I, except that in this case, the pentaerythritol tetranitrate added had a water content of 18%. After the water had been removed from the top of the melt, the material contained 4-5% water," as 'was found to be the case regardless of the original water I content. The removal of the residual water was hastened by bubbling air through the melt. In this case, the moisture content amounted to less than 0.1%

' after about 54 minutes of operation.

Example III A 5000-gram lot was prepared by mixing 2500 grams of TNT with 3500 grams of wet .PETN, having a water content of approximately 40%. The mixture was in a jacketed kettle and was heated to a temperature above the melting point of TNT. After fusion was complete and thorough mixture had been obtained, the water was removed from the surface by dippin The mixture was then allowed to stand at a temperature above the fusion point until the clearness oi the melt showed the elimination of substantially all the water.

Example IV Similar amounts of TNT and wet PE'I'N were brought into a jacketed sheet-iron pot containing water. Steam was run into the mixture to agitate the same and to raise the temperature above the melting point of the TNT. After thorough mixture, the supernatant water was removed from the surface. Air was caused to pass through the fused mixture while it was maintained at an elevated temperature, and a dry mixture was thereby obtained.

The advantages of the process according to our invention can be readily appreciated. As hasslready been stated, the use of wet pentaerythritol tion 01' melts, since it does not form lumps on foregoing. It will be understood, however, that many details in compositions and methods of procedure can be introduced without departure from the scope of the invention. We intend to be limited therefore only by the following patent claims. I

We claim:

1. The method of preparing cast explosive charges, which comprises blending trlnitrotoluene and wet pentaerythritol tetranitrate, raising the temperature of the mixture to a point where the trinitrotoluene becomes molten, removing theseparated water from the surface of the blended charge and further reducing the water content by evaporation at an elevated temperature.

2. The method of preparing cast explosive charges, which comprises preparing ,a blend of -75% pentaerythritol tetranitrate and 65-25% trinitrotoluene by mixing trinitrotoluene and pentaerythritol tetranitrate having a water content greater than 10%, heating to form a melt, removing the separated water from the surface of the blended charge, and bringing about further drying by passage of air through the melt,

3. The method of preparing cast explosive charges, which comprises adding to molten trinitrotoluene pentaerythritol tetranitrate wet with more than 10% of water, removing the separated water from the surface of the blended charge and further reducing the water content by evaporation at an elevated temperature.

4. The method of preparing cast explosive charges, which comprises preparing a blend of 35-75% penta'erythritol tetranitrate and 65-25% trinitrotoluene by adding to the trlnitrotoluene in molten condition pentaerythrltol tetranitrate having a water content in excess of 10%, remove;

' ing the separated water from the surface of the tetranitrate avoids theloss of time consumed in ther advantage that the wet material is considerably more suitable than the dry for the preparablended charge and bringing about further drying by passage of air through the melt.

- 5. The method of preparing cast explosive charges; which comprises adding to molten trinitrotoluene pentaerythritol tetranitrate wet with more than 10% of water, removing the separated water from the surface of the blended charge and further reducing the water content by evaporation.

CLYDE o. DAVIS. wmlum E. xmsr. 

